For inverter repairers, static inspection of inverter drive circuits and CPU boards is not a difficult task. So how can we make this easy task more efficient? Below, the editor from Inverter Repair from Scratch will share some insights on inverter repair.
Static measurement of negative pressure voltage regulator
When the module fails, the negative voltage regulator diode it drives is easily damaged, and vice versa. This refers to ZD2~ZD5 ( 5.1V ) in Figure 1. The testing method is the same as that for ordinary diodes; see Section 2 of Chapter 2 for details.
Inverter drive circuit
2. Static in-line measurement of driving optocouplers
The KVFC+415GR frequency converter uses two types of optocouplers for its module drive: TLP351 and HCPL3120, which are interchangeable. Static measurement with a multimeter can roughly determine their condition; in-circuit measurement results are shown in Table 7.3.2 . The structures of TLP351 and HCPL3120 are shown in Figure 2.
Reference table of static in-circuit measurement results for inverter drive optocoupler
3. Static inspection of the CPU board
To avoid short-circuiting the power supply when the CPU board is damaged, the impedance between the positive and negative terminals of each power output terminal on the CPU board should be measured before connecting the CPU board. Table 3 provides reference impedance values between the positive and negative terminals of each power supply when the CPU board is functioning normally. (The data in the table were measured using the resistance setting of a digital multimeter.)
The impedance between the positive and negative terminals of each power supply on the inverter CPU board (as long as it is not significantly different from the data in the table).
Friendly reminder: The + 3.3V measurement is done at the +3.3V test point on the CPU board . +5V, -15V, and +15V are measured at socket CN21.
For measurement , +10V and +24V can be directly measured on the CPU board terminal block. (See Figure 4.)
Inverter CPU board components and socket signal names
After replacing the components in the above static maintenance process, dynamic maintenance will then be carried out.
